by shnar
Yes, the rest of the tiles go underneath the Stairway tile (and it's not just after #10, it's a random of 3).Named tiles are really just decoration, except in the adventures that specify use XYZ tile.
Yes, you draw and place a Monster on every tile you draw. The skulls have nothing to do with the normal mechanics of the game (there's only one or two adventures that do something special with the skull tiles). The tiles to pay attention to are the ones with a black triangle instead of white triangle. The black ones require you to draw an Encounter Card during the Villain phase.
-shnar